Understanding moles and molarity

In order to understand the principles of moles and molarity it is important to have a basic appreciation of the terms associated with atoms, atomic structure and molecules. These terms are often perceived as confusing or complicated, and the following subsections are aimed at demystifying moles and molarity. 

A mole is a term that represents a number just like the word dozen represents 12 , the word mole represents 6.02 x 10 (or 602 216 900 000 000 000 

000000). The term mole, while initially confusing, is extremely useful. To give an example if we were to count the number of water molecules in a single drop it would be around 10 trillion (10000000000000), so rightly or wrongly chemists argue that it is easier to quantify such numbers in moles and thus cut down on the number of zeros  

This number is Avogadro s number , named after the Italian physics professor who proposed that equal volumes of different gases at the same temperature contain the same number of molecules. In its simplest form, 1 mol of any substance contains 6.02 x 10 atoms or molecules of that substance, and as this relationship was first put forward by Avogadro they named this number after him. 

A defined mass of an element (its atomic weight) contains an exact number of atoms, that is, Avogadro s number. Therefore, for any given molecule, one mole of the substance has a mass (in grams) equal (numerically) to the atomic mass of the molecule. One mole is the number of atoms in exactly 12 thousandths of a kilogram (i.e. 12 g) of carbon ( C), which is the most abundant isotope of carbon. 

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